<template>
    <div class="pagination">
        <button :disabled="pageNo == 1" @click="$emit('getPageNo',pageNo-1)">上一页</button>
        <button v-if="startAndEnd.start>1" @click="$emit('getPageNo',1)">1</button>
        <button v-if="startAndEnd.start>2">···</button>
        <!-- v-for可以遍历数组|Number|String|对象|Iterable -->
        <button 
        v-for="(page,index) in startAndEnd.end" 
        v-if="page>=startAndEnd.start"
        :key="index"
        @click="$emit('getPageNo',page)"
        :class="{active:page == pageNo}"
        >{{page}}</button>

        <button v-if="startAndEnd.end<totalPage-1">···</button>
        <button v-if="startAndEnd.end<totalPage" @click="$emit('getPageNo',totalPage)">{{totalPage}}</button>
        <button :disabled="pageNo == totalPage" @click="$emit('getPageNo',pageNo+1)">下一页</button>

        <button style="margin-left: 30px">共 {{total}} 条</button>
    </div>
</template>

<script>
export default {
    name: "Pagination",
    props:['pageNo','pageSize','total','continues'],
    computed:{
        totalPage(){
            return Math.ceil(this.total/this.pageSize) 
        },
        //计算连续页码的起始数字和结束数字
        startAndEnd(){
            const {continues,totalPage,pageNo} = this
            let start = 0,end = 0;
            if(continues > totalPage){
                start = 1;
                end = totalPage
            }else{
                start = pageNo - parseInt(continues/2);
                end = pageNo + parseInt(continues/2);
                if(start<1){
                    start = 1;
                    end = continues;
                }
                if(end>totalPage){
                    end = totalPage;
                    start = totalPage - continues + 1;
                }
            }
            return {start,end}
        }
    },
    methods: {
        
    },
}
</script>

<style lang="less" scoped>
.pagination {
    text-align: center;
    button {
        margin: 0 5px;
        background-color: #f4f4f5;
        color: #606266;
        outline: none;
        border-radius: 2px;
        padding: 0 4px;
        vertical-align: top;
        display: inline-block;
        font-size: 13px;
        min-width: 35.5px;
        height: 28px;
        line-height: 28px;
        cursor: pointer;
        box-sizing: border-box;
        text-align: center;
        border: 0;

        &[disabled] {
            color: #c0c4cc;
            cursor: not-allowed;
        }

        &.active {
            cursor: not-allowed;
            background-color: #409eff;
            color: #fff;
        }
    }
}
</style>
